Ideal is 150 to 155.

164 is not that bad if you have a grunty sail and are sailing in a bit of pressure. You do suffer a bit downwind with depth. We were originally 186 when we bought the boat and suffered bad in the light stuff and downwinds.

Did not change the mast settings that much. From memory we ran about 35mm to 45mm on the daimonds and mast rake at the lower gundgeon.